The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Slide bearings are generally known in the art. Generally, a slide bearing includes a thrust bearing which, on a side facing a crankshaft, is provided with a bearing shell. The inside of the bearing shell and the surface of the crankshaft delimit a bearing gap through which a lubricant flows during operation. The lubricant is usually supplied through a groove centrally disposed in the bearing shell.
Generally, the shafts of internal combustion engines in motor vehicles are supported by slide bearings. For optimum lubrication, the slide bearings are supplied in most cases with oil made to flow through one of the bearing shells by an oil pump. The oil is pressed into the bearing under a certain pressure. Oil pressure is needed to provide the bearings with a sufficient supply of oil because the oil flows off into gaps required for construction-related reasons. A large radial gap causes removal of an undesirably large amount of oil and, therefore, a dangerous pressure drop in the bearing. A pressure drop can cause a lubricant film to deteriorate which may result in faster wear of the moving parts. For safe operation, therefore, a sufficiently high oil pressure in the bearing is needed.
In operation, the gap in the bearing may increase, for example, as a result of thermal expansion. To keep a constant oil pressure in the bearing, pumps with an elevated pumping power can be used to offset this increase. Problems may arise, however, in modern engines that have light-metal housings in which component parts having different thermal expansion coefficients interact.
The prior art describes the use of cast beds/cast-bed bearings in light-metal crankshaft housings for the purpose of receiving the bearing shells. This is intended to reduce the different radial widenings and thus the gap-forming process between different structural components, a process that can lead to increased lubricant outflow. Such solutions, however, are used at the expense of engine weight and they raise production costs.
DE 198 18 120 describes a slide bearing for crankshafts in which between the bearing shell and the thrust bearing there is provided a compensation system, the thermal expansion of which is greater than that of the thrust bearing. This compensation system is supposed to counteract the temperature-dependent widening of the bearing gap and thus an increase in lubricant outflow.